Cluster headache (CH) is a primary headache by definition not caused
by any known underlying structural pathology. However, symptomatic
cases have been described, for example, tumors, particularly
pituitary adenomas, malformations, and infections/inflammations. The
evaluation of CH is an issue unresolved.A 46-year-old man presented with a 5-month history of
side-locked attacks of an excruciating stabbing and boring
left-sided pain located in the orbit. He satisfied the revised
International Classification of Headache Disorders criteria for CH.
His medical and family histories were unremarkable. A diagnosis of
CH was made. The patient partially responded to symptomatic
treatment. Owing to the relatively late onset of CH an enhanced
magnetic resonance imaging was ordered to rule out an underlying
lesion. It was performed after 1 month and displayed a pituitary
adenoma. Evaluations revealed a prolactinoma. After treatment with
bromocriptine, the headache attacks resolved completely. Although I
cannot exclude an unintentional comorbidity, in my opinion, the
co-occurrence of a prolactinoma with unilateral headache, in a
hitherto headache-free man, points toward the fact that in this case
the CH was caused or triggered by the prolactinoma. The headache
attacks resolved completely after the bromocriptine treatment and
the patient also remained headache free at the follow-up. The
response of the headache to sumatriptan and other typical CH
medications does not exclude a secondary form. Symptomatic CHs
responsive to this therapy have been described. Associated cranial
lesions such as tumours have been reported in CH patients and the
attacks may be clinically indistinguishable from the primary form.
Neuroimaging, preferably contrast-enhanced magnetic resonance
imaging should always be considered in patients with cluster
headache despite normal neurological examination. Late-onset cluster
headache represents a condition that requires careful evaluation.
Prolactinoma can present as cluster headache.

Cluster headache (CH) is a primary headache, by definition not
caused by any underlying structural pathology and belonging to the
group of trigeminal-autonomic cephalalgias [1].
CH is the most frequent syndrome in this group. The characteristic
symptoms are strictly unilateral head pain (mainly around orbital
and temporal regions) and associated ipsilateral cranial autonomic
features. The headache usually lasts 45 to 90 minutes, but can range
between 15 and 180 minutes. A circannual and circadian pattern is
typical. Although uncommon, symptomatic cases of CH have been
described, for example, tumors, particularly pituitary adenomas,
malformations, and infection/inflammation [2].
The question whether patients with CH should undergo neuroimaging to
exclude a causal underlying structural lesion is unresolved.
Symptomatic CH due to prolactinoma is rare, although reported [2].
I here report a case of prolactinoma, the symptoms of which fully
comply with the criteria of cluster headache [1].
Therefore, the importance of accurate neuroimaging in CH patients is
emphasized.

Case Report

A
46-year-old man presented with a 5-month history of side-locked
attacks of an excruciating stabbing and boring left-sided pain
located in the orbit. The attacks were associated with nasal
obstruction, conjunctival injection, restlessness, nausea and
photophobia/phonophobia. No continuous background pain was
identified. The duration of the attacks was about 40 - 50 minutes
and the frequency 3 per 24 hours, 3 to 4 days a week and they also
occurred during the night. There was no history of headache. His
medical and family history was otherwise unremarkable. He was not on
any medications and used no drugs. Vital signs, physical
examination, and neurological examination were normal. Routine
laboratory testing was normal. He satisfied the revised
International Classification of Headache Disorders criteria for CH.
A diagnosis of CH was made and subcutaneous sumatriptan as well as
oral sumatriptan were prescribed along with oral verapamil 240 to
480 mg daily. The patient responded partially to the treatment with
relief within 15 to 20 minutes (subcutaneous sumatriptan) and the
attacks were reduced in frequency within 7 days (1 attack/d). A
follow-up was planned. Owing to the relatively late onset of CH an
enhanced magnetic resonance imaging (MRI) was ordered to rule out an
underlying lesion. It was performed after 1 month and displayed a
pituitary adenoma (Fig.
1a). The serum prolactin was significantly elevated (3,000
μg/L, normal range
< 15
μg/L). The remainder of the pituitary function was normal. A
pituitary prolactinoma was diagnosed and the patient was prescribed
bromocriptine, half a 2.5 mg tablet taken at bedtime. The dose was
gradually increased every 3 to 7 days up to 7.5 mg. The patient’s
headache remained in the improved state with only sporadic headache
attacks at follow-up after 2 months. Visual fields were normal. An
MRI scanning performed after about 4 months displayed reduction in
tumour volume (Fig.
1b). The patient now reported that the headache attacks had
completely resolved.CH treatment was discontinued. He remained
headache free and had not experienced any headache attacks at
follow-up after 5 years despite discontinuation of CH treatment.
Serum prolactin levels remains slightly elevated.

The
case study highlights a patient with CH responding to treatment.
Evaluation revealed a pituitary prolactinoma. The patient satisfied the revised International Classification of
Headache Disorders criteria for CH [1].
Although I cannot exclude an unintentional comorbidity, in my
opinion, the co-occurrence of a pituitary prolactinoma with
unilateral headache, in a hitherto headache-free man, points towards
the fact that in this case the CH was caused or triggered by the
prolactinoma. The headache attacks resolved completely after
treatment of the prolactinoma.

The
response of the headache to sumatriptan and other typical CH
medications does not exclude a secondary form [3,
4].
Associated cranial lesions such as tumours have been reported in CH
patients and the attacks may be clinically indistinguishable from
the primary form [3,
5].
Mainardi et al [2]
identified 156 secondary cluster-like headache (CLH) cases published
from 1975 to 2008. They found in the review that vascular
pathologies, for example, intracranial aneurysms and dural fistulas
were the first cause of secondary CH, followed by tumours and
inflammatory/infectious diseases. Pituitary adenomas accounted for
3% of secondary CH cases. Prolactinomas were the most common tumour
of the pituitary adenomas.

The
pathophysiology of CH is not well known. The most widely accepted
theory is that primary CH is characterized by hypothalamic
activation with secondary activation of the trigeminal-autonomic
reflex, probably by a trigeminal-hypothalamic pathway [1].
The exact pathophysiology in our case is unknown. A structural
lesion may cause autonomic imbalance, resulting in periodic
fluctuations in the activity of the autonomic nervous system,
ultimately leading to an attack-wise presentation of the symptoms.
Differences in the individual threshold for triggering the
parasympathetic trigeminal reflexes may also play a role [6,
7]. A
number of cases of symptomatic CH reported have had sellar/parasellar
abnormality as well as in this case. The sympathetic,
parasympathetic and sensory fibres of the trigeminal nerve gather as
a plexus in the sinus cavernosus/hypophyseal region. Thus, nerves in
this region appear to be of importance to produce symptoms of CH [1].

Attempts have been made to define red flags indicating a secondary
cause when cluster-like headache appears for the first time [2].
Compared with primary CH, secondary CH presents at an older age
(about 42 y). A late onset represents a condition that requires
careful evaluation [2].
The authors of that study also emphasize in their report that, at
first observation, 50% of patients with secondary CH presented as
cases fulfilling the criteria for CH, perfectly mimicking CH.
Therefore, the likelihood that a secondary cause is responsible for
a clinical picture mimicking a primary CH, albeit low, should always
be considered [2].

This
opinion is in accordance with the review by Favier et al and
Wilbrink et al
[5,
6] who
recommend neuroimaging in all patients with trigeminal-autonomic
cephalalgias. MRI is the preferred procedure for imaging in CH cases
because of its greater sensitivity to vascular disease, tumor,
demyelinating disease, and infection/inflammation [2,
6].

Conclusions

CH
might be the presenting symptom of a pituitary prolactinoma even in
typical forms of that headache. Contrast-enhanced MRI including
different techniques should always be considered in patients with
CH. Late-onset CH represents a condition that requires careful
evaluation.

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http://dx.doi.org/10.4021/jmc1379e
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